John Britt's Snowflake Crackle - The cone 6 oxidation glazes - Electric Mid&Hi Fired Ceramics2024-03-29T05:20:54Zhttps://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150249&xg_source=activity&feed=yes&xn_auth=noAbout that Snowflake crackle…tag:cone6pots.ning.com,2019-02-19:2103784:Comment:1525822019-02-19T20:18:12.981ZJChttps://cone6pots.ning.com/profile/JC
<p>About that Snowflake crackle #4, I used that on several clay bodies and found I got a much better, more predictable result by spraying it on rather than dipping. It tends to settle very quickly and the talc/nepheline combo tends to clump when dipped. <br/><br/>Very nice finish when sprayed though.</p>
<p>About that Snowflake crackle #4, I used that on several clay bodies and found I got a much better, more predictable result by spraying it on rather than dipping. It tends to settle very quickly and the talc/nepheline combo tends to clump when dipped. <br/><br/>Very nice finish when sprayed though.</p> I will try this next test go…tag:cone6pots.ning.com,2018-08-30:2103784:Comment:1504192018-08-30T04:18:53.700ZPenny Berglundhttps://cone6pots.ning.com/profile/PennyBerglund
<p>I will try this next test go round. It would make sense with the large bubbles I got at times. But it still doesn't explain the pinholes prevalent on the undersides of pieces that had an even glaze surface and no bubbled lava effects.</p>
<p>I will try this next test go round. It would make sense with the large bubbles I got at times. But it still doesn't explain the pinholes prevalent on the undersides of pieces that had an even glaze surface and no bubbled lava effects.</p> Snowflake glazes, like high-m…tag:cone6pots.ning.com,2018-08-29:2103784:Comment:1503172018-08-29T20:40:26.209ZNorm Stuarthttps://cone6pots.ning.com/profile/NormStuart
<p>Snowflake glazes, like high-magnesium crawl glazes, have a tendency to fall off ware before it's melted in places where gravity does not favor it remaining in place.</p>
<p>Fire a bowl upside-down and you'll most likely discover the snowflake glaze is fine on the outside of the bowl but the glaze coating is thin and spotty on the upside-down inside of the bowl.</p>
<p></p>
<p>I experience the same problem with two layer oil-spot glazes where you place a runny top coat over an iron-rich base…</p>
<p>Snowflake glazes, like high-magnesium crawl glazes, have a tendency to fall off ware before it's melted in places where gravity does not favor it remaining in place.</p>
<p>Fire a bowl upside-down and you'll most likely discover the snowflake glaze is fine on the outside of the bowl but the glaze coating is thin and spotty on the upside-down inside of the bowl.</p>
<p></p>
<p>I experience the same problem with two layer oil-spot glazes where you place a runny top coat over an iron-rich base glaze. But in this instance the runny top glaze slides off <strong>after</strong> it's melted. Gravity is one of those laws or something like that.</p> I contacted John Britt, and o…tag:cone6pots.ning.com,2018-08-29:2103784:Comment:1501232018-08-29T16:49:45.759ZPenny Berglundhttps://cone6pots.ning.com/profile/PennyBerglund
<p>I contacted John Britt, and other than trying other clay bodies, he had no suggestions. I did find it interesting that the worst problems were on the outsides/undersides of the pieces. Any idea about why that would be?</p>
<p>Penny</p>
<p>I contacted John Britt, and other than trying other clay bodies, he had no suggestions. I did find it interesting that the worst problems were on the outsides/undersides of the pieces. Any idea about why that would be?</p>
<p>Penny</p> Thanks! I will keep testing.…tag:cone6pots.ning.com,2018-07-29:2103784:Comment:1500862018-07-29T21:15:01.602ZPenny Berglundhttps://cone6pots.ning.com/profile/PennyBerglund
<p>Thanks! I will keep testing. I will see what I can get in the broad area I call local and will post results. I think you are right about the clay. I was very careful with the bisque fire.<br></br> <br></br> <cite>Norm Stuart said:</cite></p>
<blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150084&xg_source=msg_com_forum#2103784Comment150380"><div><div class="xg_user_generated"><p>I can't guarantee…</p>
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<p>Thanks! I will keep testing. I will see what I can get in the broad area I call local and will post results. I think you are right about the clay. I was very careful with the bisque fire.<br/> <br/> <cite>Norm Stuart said:</cite></p>
<blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150084&xg_source=msg_com_forum#2103784Comment150380"><div><div class="xg_user_generated"><p>I can't guarantee we've tried Snowflake with all of these clays, but these are our combined clay orders over the past five years.</p>
<p></p>
<table width="740">
<tbody><tr><td width="75">WC 371</td>
<td width="665">Big Pot Clay 60 mesh sand</td>
</tr>
<tr><td>WC 373</td>
<td>Dark Brown Clay -- fine sand</td>
</tr>
<tr><td>WC 376</td>
<td>L.B. Blend Clay 60 mesh sand</td>
</tr>
<tr><td>WC 381</td>
<td>Big White Clay with grog & sand</td>
</tr>
<tr><td>WC 384</td>
<td>Dave's Porcelain</td>
</tr>
<tr><td>WC 398</td>
<td>WS-4 gray/white with fine sand</td>
</tr>
<tr><td>WC 429</td>
<td>RSMC Red Clay</td>
</tr>
<tr><td>WC 894</td>
<td>Half & Half SC</td>
</tr>
<tr><td>WC-353</td>
<td>Paper Clay Cone 10</td>
</tr>
<tr><td>WC-370</td>
<td>Amador Cone 10 - densifies nicely at Cone 6</td>
</tr>
<tr><td>WC-390</td>
<td>Laguna Red</td>
</tr>
<tr><td>WC-391</td>
<td>B-3 Brown Black</td>
</tr>
<tr><td>WC-395</td>
<td>Porcelain Five</td>
</tr>
<tr><td>WC-400</td>
<td>Morrocan Sand</td>
</tr>
<tr><td>WC-402</td>
<td>Half n Half - pinholes with Ferro 5301</td>
</tr>
<tr><td>WC-412</td>
<td>Stoney White - new</td>
</tr>
<tr><td>WC-423</td>
<td>Greystone - contains magnesium or zinc which turns some blue and green glazes brown</td>
</tr>
<tr><td>WC-436</td>
<td>B Mix 5 with Grog</td>
</tr>
<tr><td>WC-438</td>
<td>Red B-Mix with grog Easy Dry</td>
</tr>
<tr><td>WC-841</td>
<td>Danish White Clay</td>
</tr>
<tr><td>WC-842</td>
<td>Danish White Clay -- fine sand</td>
</tr>
<tr><td>WC-851</td>
<td>52 Buff</td>
</tr>
<tr><td>WC-861</td>
<td>Haggi Porcelain</td>
</tr>
<tr><td>WC-866</td>
<td>Electric Brown</td>
</tr>
<tr><td>WC-886</td>
<td>B Mix with Grog Paper - extremely problematic blistering, order only WC-353</td>
</tr>
</tbody>
</table>
<p><cite>Penny Berglund said:</cite></p>
<blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150379&xg_source=msg_com_forum#2103784Comment150379"><div><p>I will try another clay body. I will also ask my supplier what they think. I am getting good crackle even where it is thin which would mean I won't have to go so nuts with the thicker glaze layer.</p>
<p>Is there a Laguna clay body that has worked for you with this glaze? IMCO? I can get clay at Clay Art Center in Tacoma, and I will be in Seattle next week and can get the clay bodies that Seattle Pottery Supply makes up as well. Since I am in the gorge now, it is also possible to make a trip to Portland to try what Georgies makes up.</p>
<p>Penny</p>
<blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150084&xg_source=msg_com_forum#2103784Comment150084"><div><div class="xg_user_generated"><blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150080&xg_source=msg_com_forum#2103784Comment150080"></blockquote>
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</blockquote>
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</blockquote> I can't guarantee we've tried…tag:cone6pots.ning.com,2018-07-29:2103784:Comment:1503802018-07-29T21:03:40.064ZNorm Stuarthttps://cone6pots.ning.com/profile/NormStuart
<p>I can't guarantee we've tried Snowflake with <strong>all</strong> of these clays, but these are our combined clay orders over the past five years.</p>
<p></p>
<table width="740">
<tbody><tr><td width="75">WC 371</td>
<td width="665">Big Pot Clay 60 mesh sand</td>
</tr>
<tr><td>WC 373</td>
<td>Dark Brown Clay -- fine sand</td>
</tr>
<tr><td>WC 376</td>
<td>L.B. Blend Clay 60 mesh sand</td>
</tr>
<tr><td>WC 381</td>
<td>Big White Clay with grog & sand</td>
</tr>
<tr><td>WC…</td>
</tr>
</tbody>
</table>
<p>I can't guarantee we've tried Snowflake with <strong>all</strong> of these clays, but these are our combined clay orders over the past five years.</p>
<p></p>
<table width="740">
<tbody><tr><td width="75">WC 371</td>
<td width="665">Big Pot Clay 60 mesh sand</td>
</tr>
<tr><td>WC 373</td>
<td>Dark Brown Clay -- fine sand</td>
</tr>
<tr><td>WC 376</td>
<td>L.B. Blend Clay 60 mesh sand</td>
</tr>
<tr><td>WC 381</td>
<td>Big White Clay with grog & sand</td>
</tr>
<tr><td>WC 384</td>
<td>Dave's Porcelain</td>
</tr>
<tr><td>WC 398</td>
<td>WS-4 gray/white with fine sand</td>
</tr>
<tr><td>WC 429</td>
<td>RSMC Red Clay</td>
</tr>
<tr><td>WC 894</td>
<td>Half & Half SC</td>
</tr>
<tr><td>WC-353</td>
<td>Paper Clay Cone 10</td>
</tr>
<tr><td>WC-370</td>
<td>Amador Cone 10 - densifies nicely at Cone 6</td>
</tr>
<tr><td>WC-390</td>
<td>Laguna Red</td>
</tr>
<tr><td>WC-391</td>
<td>B-3 Brown Black</td>
</tr>
<tr><td>WC-395</td>
<td>Porcelain Five</td>
</tr>
<tr><td>WC-400</td>
<td>Morrocan Sand</td>
</tr>
<tr><td>WC-402</td>
<td>Half n Half - pinholes with Ferro 5301</td>
</tr>
<tr><td>WC-412</td>
<td>Stoney White</td>
</tr>
<tr><td>WC-423</td>
<td>Greystone - contains something (zinc?) which turns many blue and green glazes to brown</td>
</tr>
<tr><td>WC-436</td>
<td>B Mix 5 with Grog</td>
</tr>
<tr><td>WC-438</td>
<td>Red B-Mix with grog Easy Dry</td>
</tr>
<tr><td>WC-841</td>
<td>Danish White Clay</td>
</tr>
<tr><td>WC-842</td>
<td>Danish White Clay -- fine sand</td>
</tr>
<tr><td>WC-851</td>
<td>52 Buff</td>
</tr>
<tr><td>WC-861</td>
<td>Haggi Porcelain</td>
</tr>
<tr><td>WC-866</td>
<td>Electric Brown</td>
</tr>
<tr><td>WC-886</td>
<td>B Mix with Grog Paper - extremely problematic blistering, order only WC-353</td>
</tr>
</tbody>
</table>
<p><cite>Penny Berglund said:</cite></p>
<blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150379&xg_source=msg_com_forum#2103784Comment150379"><div><p>I will try another clay body. I will also ask my supplier what they think. I am getting good crackle even where it is thin which would mean I won't have to go so nuts with the thicker glaze layer.</p>
<p>Is there a Laguna clay body that has worked for you with this glaze? IMCO? I can get clay at Clay Art Center in Tacoma, and I will be in Seattle next week and can get the clay bodies that Seattle Pottery Supply makes up as well. Since I am in the gorge now, it is also possible to make a trip to Portland to try what Georgies makes up.</p>
<p>Penny</p>
<blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150084&xg_source=msg_com_forum#2103784Comment150084"><div><div class="xg_user_generated"><blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150080&xg_source=msg_com_forum#2103784Comment150080"></blockquote>
</div>
</div>
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</blockquote> I will try another clay body.…tag:cone6pots.ning.com,2018-07-29:2103784:Comment:1503792018-07-29T20:47:11.652ZPenny Berglundhttps://cone6pots.ning.com/profile/PennyBerglund
<p>I will try another clay body. I will also ask my supplier what they think. I am getting good crackle even where it is thin which would mean I won't have to go so nuts with the thicker glaze layer.</p>
<p>Is there a Laguna clay body that has worked for you with this glaze? IMCO? I can get clay at Clay Art Center in Tacoma, and I will be in Seattle next week and can get the clay bodies that Seattle Pottery Supply makes up as well. Since I am in the gorge now, it is also possible to make a trip…</p>
<p>I will try another clay body. I will also ask my supplier what they think. I am getting good crackle even where it is thin which would mean I won't have to go so nuts with the thicker glaze layer.</p>
<p>Is there a Laguna clay body that has worked for you with this glaze? IMCO? I can get clay at Clay Art Center in Tacoma, and I will be in Seattle next week and can get the clay bodies that Seattle Pottery Supply makes up as well. Since I am in the gorge now, it is also possible to make a trip to Portland to try what Georgies makes up.</p>
<p>Penny<br/> <br/> <cite>Norm Stuart said:</cite></p>
<blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150084&xg_source=msg_com_forum#2103784Comment150084"><div><div class="xg_user_generated"><p>From the photos, I believe your problem lies exclusively with the clay used continuing to off-gas in an interaction with the glaze.</p>
<p><strong>I'd try again with a different clay, as I've never seen this glaze pinhole</strong>, although it is an interesting look.</p>
<p>As an example, we've always had a pinhole problem with <strong>Laguna "Half and Half"</strong> clay when <strong>a fluorine-based glaze is applied</strong> (Ferro Frit 5301).</p>
<p>There's obviously some raw material in the "Half and Half" clay, which is not present in other Laguna clays, which the Fluorine flux in Ferro Frit 5301 decomposes during a Cone 6 firing.</p>
<p>Even after refiring the "Half and Half' with 5301 glazes three times, pinholes continue to develop, so it's a very long-lived reaction.</p>
<p></p>
<p><strong>The typical look of the Snow Flake glaze</strong></p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/3127178959?profile=original" target="_self"><img src="http://storage.ning.com/topology/rest/1.0/file/get/3127178959?profile=original" class="align-left" width="360"/></a></p>
<p></p>
<p><img src="http://storage.ning.com/topology/rest/1.0/file/get/3127179054?profile=original" alt="http://storage.ning.com/topology/rest/1.0/file/get/3127179054?profile=original" class="shrinkToFit" width="1049" height="588"/></p>
<p><cite>Penny Berglund said:</cite></p>
<blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150080&xg_source=msg_com_forum#2103784Comment150080"><div><p>I did a new test run with a much better bisque protocol and a glaze test firing. I also ran a small test with a new batch of neph sy. I did see improvement in the cratering I experienced before along with large holes. I had problems on the tops of the bowls with crawling, likely due to very thick glaze application and I still had pinholing on the undersides of bowls but not at bad. Glazes were applied on different days to the underside to allow the inside of the bowls to dry and then dried completely before firing.</p>
<p>New neph sy small test was essentially the same.</p>
<p>Have any of you succeeded with this glaze? I will try to spray the glaze on instead of pouring and may even go to bisque between layers of glaze if I need to. Mr. Britt says this needs an application of 3 to 6 mm of glaze.</p>
<p>Penny</p>
<p>Comparisons show items from first firing and from this latest test</p>
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</blockquote> From the photos, I believe yo…tag:cone6pots.ning.com,2018-07-29:2103784:Comment:1500842018-07-29T20:27:08.317ZNorm Stuarthttps://cone6pots.ning.com/profile/NormStuart
<p>From the photos, I believe your problem lies exclusively with the clay used continuing to off-gas in an interaction with the glaze.</p>
<p><strong>I'd try again with a different clay, as I've never seen this glaze pinhole</strong>, although it is an interesting look.</p>
<p>As an example, we've always had a pinhole problem with <strong>Laguna "Half and Half"</strong> clay when <strong>a fluorine-based glaze is applied</strong> (Ferro Frit 5301).</p>
<p>There's obviously some raw material in…</p>
<p>From the photos, I believe your problem lies exclusively with the clay used continuing to off-gas in an interaction with the glaze.</p>
<p><strong>I'd try again with a different clay, as I've never seen this glaze pinhole</strong>, although it is an interesting look.</p>
<p>As an example, we've always had a pinhole problem with <strong>Laguna "Half and Half"</strong> clay when <strong>a fluorine-based glaze is applied</strong> (Ferro Frit 5301).</p>
<p>There's obviously some raw material in the "Half and Half" clay, which is not present in other Laguna clays, which the Fluorine flux in Ferro Frit 5301 decomposes during a Cone 6 firing.</p>
<p>Even after refiring the "Half and Half' with 5301 glazes three times, pinholes continue to develop, so it's a very long-lived reaction.</p>
<p></p>
<p><strong>The typical look of the Snow Flake glaze</strong></p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/3127178959?profile=original" target="_self"><img src="http://storage.ning.com/topology/rest/1.0/file/get/3127178959?profile=original" class="align-left" width="360"/></a></p>
<p></p>
<p><img src="http://storage.ning.com/topology/rest/1.0/file/get/3127179054?profile=original" alt="http://storage.ning.com/topology/rest/1.0/file/get/3127179054?profile=original" class="shrinkToFit" width="1049" height="588"/></p>
<p><cite>Penny Berglund said:</cite></p>
<blockquote cite="http://cone6pots.ning.com/forum/topics/john-britt-s-snowflake-crackle-the-cone-6-oxidation-glazes?commentId=2103784%3AComment%3A150080&xg_source=msg_com_forum#2103784Comment150080"><div><p>I did a new test run with a much better bisque protocol and a glaze test firing. I also ran a small test with a new batch of neph sy. I did see improvement in the cratering I experienced before along with large holes. I had problems on the tops of the bowls with crawling, likely due to very thick glaze application and I still had pinholing on the undersides of bowls but not at bad. Glazes were applied on different days to the underside to allow the inside of the bowls to dry and then dried completely before firing.</p>
<p>New neph sy small test was essentially the same.</p>
<p>Have any of you succeeded with this glaze? I will try to spray the glaze on instead of pouring and may even go to bisque between layers of glaze if I need to. Mr. Britt says this needs an application of 3 to 6 mm of glaze.</p>
<p>Penny</p>
<p>Comparisons show items from first firing and from this latest test</p>
</div>
</blockquote> I did a new test run with a m…tag:cone6pots.ning.com,2018-07-29:2103784:Comment:1500802018-07-29T16:22:48.207ZPenny Berglundhttps://cone6pots.ning.com/profile/PennyBerglund
<p>I did a new test run with a much better bisque protocol and a glaze test firing. I also ran a small test with a new batch of neph sy. I did see improvement in the cratering I experienced before along with large holes. I had problems on the tops of the bowls with crawling, likely due to very thick glaze application and I still had pinholing on the undersides of bowls but not at bad. Glazes were applied on different days to the underside to allow the inside of the bowls to dry and then dried…</p>
<p>I did a new test run with a much better bisque protocol and a glaze test firing. I also ran a small test with a new batch of neph sy. I did see improvement in the cratering I experienced before along with large holes. I had problems on the tops of the bowls with crawling, likely due to very thick glaze application and I still had pinholing on the undersides of bowls but not at bad. Glazes were applied on different days to the underside to allow the inside of the bowls to dry and then dried completely before firing.</p>
<p>New neph sy small test was essentially the same.</p>
<p>Have any of you succeeded with this glaze? I will try to spray the glaze on instead of pouring and may even go to bisque between layers of glaze if I need to. Mr. Britt says this needs an application of 3 to 6 mm of glaze.</p>
<p>Penny</p>
<p>Comparisons show items from first firing and from this latest test</p> Norm:
ASTM D-4318 based on th…tag:cone6pots.ning.com,2018-07-12:2103784:Comment:1502502018-07-12T10:11:02.729ZTom Andersonhttps://cone6pots.ning.com/profile/TomAnderson
<p>Norm:</p>
<p>ASTM D-4318 based on the Atterberg Limits, is the plasticity/ liquid test protocol used by other industries: except ours of course. Common to see numerical plasticy values used in Europe, not here of course. Some makers in Germany show carbon content, not here of course. The current testing in the US is based on a potter blowing through 10-12 bodies until they find one that does not drive them crazy.</p>
<p>Some clay deposits are going through changes: just like Custer did a few…</p>
<p>Norm:</p>
<p>ASTM D-4318 based on the Atterberg Limits, is the plasticity/ liquid test protocol used by other industries: except ours of course. Common to see numerical plasticy values used in Europe, not here of course. Some makers in Germany show carbon content, not here of course. The current testing in the US is based on a potter blowing through 10-12 bodies until they find one that does not drive them crazy.</p>
<p>Some clay deposits are going through changes: just like Custer did a few years back. The Feds only require one chemical analysis be done for the entire deposit: many are decades old. I am sure many potters are finding their favorite clays are inconsistent from order to order: too wet or too dry for example. Potters consume less than 3% of natural clays, so we are far down on the pecking order.</p>
<p></p>
<p>for porcelain: watch the shrinkage rates. The higher the shrinkage, the more plastic it is because high plasticity materials absorb more water. 10% is lower plasticity and 13% is high plasticity.</p>
<p></p>
<p>for stoneware: watch the absorption. To lower the absorption in stoneware you have to add much finer sub micron ball clays to close up the porosity of fire clays. The finer the particle, the more plastic it is.</p>
<p></p>
<p>Tom</p>
<p>I would cut and paste some materials I send out to educators on clay: but it would probably crash this site. George would not be happy.</p>